Tensioning device



Original Fil ed Feb. 25, 1946 IZI THOMAS 8. KEESLI-6. TIE :3

. EE 5 .m.

ATTORNEY FIE q containers to a rotary cooker or the like.

Patented Mar. 25, 1952 TENSIONING DEVICE Thomas B. Keesling, Campbell, Calif., assignor to Food Machinery and Chemical Corporation, San Jose, Calif., a corporation of Delaware Original application February 25, 1946, Serial No.

650,017. Divided and this application October 18, 1948, Serial No. 55,053

9 Claims. 1

This invention relates to conveyors and more particularly to a tensioning device for conveyors of the endless chain or the belt type.

The present invention is a division of my copending application Serial No. 650,017, filed February 25, 1946, for a feed mechanism for feeding With such types of feed mechanisms it is customary to maintain the endless chain conveyor at a proper tension so as to prevent drooping of the chain and jamming thereof with other parts of the feed mechanism. 4

The present invention is particularly concerned with the provision of a tensioning device so constructed as to prevent drooping ofthe chain conveyor and to further prevent jamming of the chain with other parts of the conveyor mechanism in the event the tensioning device fails to operate properly. I

Another object of this invention is to provide a safety unit for a spring tensioned'chain conveyor for preventing drooping of the chain in the event of spring breakage.

Other objects and advantages of the present invention will become more apparent from the following description in connection with the drawings in which: a

Fig. 1 is a section of a portion of a cooker showing the feed valvethereof associated with an elevator embodying the tensionin mechanism of the present invention.

Fig. 2 is a partial elevation of the present invnetion as seen from line 22 in Fig. 1.

ig. 3 is a transverse section of the elevator and tensioning device taken along line 33 in Fig. 1.

Fig. 4 is a longitudinal section, partially in ele vation taken along line 4-4 in Fig. 1.

The present invention has been illustrated in connection with a container feed mechanism for a continuous pressure cooker. Such container feed mechanism, in general, comprises a feed chute i, an elevator 2, and a feed valve 3 associated with the pressure cooker 4. I

The pressure cooker l which has been partially illustrated herein may be of any conventional construction such, for instance, as shown in U. S. Letters Patent No. Re. 15,334, dated April 11,1922, to A. R. Thompson.

Continuous cookers of this type comprise acylindrical shell it closed at its ends to provide a pressure treating chamber i2 and having an inlet opening Iii for admittingcontainers, presented thereto by the feedvalve 3, into the chamber l2. A T-shaped track it is secured to the inner wall of the shell and extends helically therealongfrom the inlet to the discharge end thereof. The containers are advanced along the track |6 by a rotary reel comprising a plurality of spider wheels l8 suitably secured to a drive shaft (not shown) journalled for rotation coaxially of the shell in a manner well known in the art. The spider wheels carry a plurality of pusher bars 20 on their periphery and longitudinally of the shell so as to form a series of pockets 2| for supporting containers along the track l6.

Secured to the shell l0 adjacentthe inlet opening l5 by means of rivets 26 is a casting 25 to which the housing 21 of the rotary feed valve 3 is secured by bolts 28. The periphery of the housing 21 has a valve outlet opening 30 adjacent to and communicating with the inlet opening |5 of the treating chamber l2 and also has a valve inlet opening 3| spaced therefrom exteriorly of the chamber. The housing 21 is provided with pressure tight bearings (not shown) at its sides and rotatably mounted within the same is a shaft disposed parallel to the drive shaft for the rotary reel. Within the housing 21 and keyed to the shaft 35 for rotation therewith is a rotary turret 36 having a plurality of peripheral pockets 31 sealed with respect to each other. Each pocket is adapted. to receive an individual container for transferring the same from the valve inlet 3| to the valve outlet 30.

The shaft 35 extends beyond one end of the housing 21 and is drivingly connected to the drive shaft for the reel H in the manner as taught in the aforesaid Thompsonpatent'Re. 15,334, so that the turret-36 is driven in synchronism with the reel l1. As seen in Fig. 1, the reel isrotated counterclockwise and the turret 36 clockwise whereby the reel pockets 2| are caused to register with the turret pockets 31 as they pass the communicating inlet and outlet openings l5 and 30 of the chamber and feed valve, respectively. The lower margin 38 of the valve inlet opening 3| is located horizontally opposite the axis of the turret. The upper margin 39 of the opening 3| is spaced peripherally from the lower margin 38 so as to permit containers'to enter the feed valve from above, that is, along a path which is substantially vertically tangent to the path the containers will travel while in the turret pockets 31. i

The elevator 2 comprises a housing having its lower end supported by a pedestal 46 and its upper end formed as a head casting 41 supported by the housing 2'! of the rotary feed valve 3. The elevator housing 45 is provided with a trough-like closure 48 intermediate the pedestal and head casting which forms a guard for moving parts of the elevator as Willlater become apparent.

The head casting 41 is formed by two circular shaped side plates 5|, each'having a downward- 1y extending section 53. Adjacent the upper margin of the inlet opening 3| each side of the valve housing 21 is provided with a boss 55, Fig. l. Flanges 51 extend horizontally from the respective side plates 5| and rest upon the bosses 55. Each adjacent side of the valve housing 2? at the lower margin of the inlet opening 3| is likewise provided with a boss 53. The flange 5'; of each side plate 5| is secured by a bolt 03, Fig. 3, to the respective bosses 55 on the valve housing and the lower ends of the plates 5| are similarly secured to the bosses 59 adjacent the lower margin of the inlet opening 3|. In this manner, the plates 5| are disposed with their inner faces flush with the end walls of the turret pockets 3? so as to permit passage of containers lengthwise therebetween.

The pedestal comprises a substantially U- shaped casting I0 having a downwardly extending sleeve II which fits over a standard I2 having a foot portion I3. Bolted, as shown at M (Figs. 1, 2, and 3), to the sides of the casting '10 are a pair of side plates "I and 70, each having a guide slot I1 formed therein. Arranged in these slots for sliding movement therealong are floating bearings I8 and I0 formed as a part of, a

yoke 80, later to be more fully described. A shaft 85 is supported for rotation in the floating bearings I8 and I9 and has a sprocket 00 secured thereto by set screws 81, as shown in Figs. 3 and 4.

The circular section of each side plate 5| is provided with a laterally projecting bearing (not shown) and an elevator drive shaft 92 is supported in these bearings for rotation about an axis parallel to the shaft 35. A drive sprocket 93 is keyed to the shaft 92 for rotation therewith between the side plates 5| and one end of the shaft extends beyond the head casting for driving connection, in a conventional manner, to the shaft 35, for example, in the same manner as the latter is connected to the drive shaft of the rotary reel.

Trained around the sprockets 93 and 00 is an endless elevator chain I00. The lower reach of chain I00 extends substantially parallel to a chord line struck across the periphery of the housing 2] from upper to lower margins 39 and 38, respectively, of the inlet opening 3|. As best seen in Fig. 1 the lower reach of the chain I00 is spaced from the inlet opening 3| to permit passage of containers between the chain and the turret housing 21. The upper reach of the elevator chain I00 is also inclined and is supported parallel to an elevator track I05, as shown in Fig. 1. The elevator track I05 comprises two angleirons I00 and I01, Fig. 3, spaced from each other by U straps I08, Fig. 1. The straps I08 are welded to the lower faces of inwardly extending flanges I09 and H0 of the angle irons and have a chain supporting channel III welded to their recessed portion.

The trough-like closure 48, mentioned above, has its open upper edges secured by bolts II5, Fig. 2, to the outer faces of vertical flanges Ill and H8 of the angle irons I06 and I01, respectively. The upper end of the closure 48 fits between the side plates 5| and each side of the closure, as well as the. upper ends of the angles I06 and I01, is secured to the respective side plates 5| by machine bolts I20, Fig. 1. The lower end of the closure 48 fits between the side plates 15 and I6 which are secured to the casting I0 of the pedestal 46. Each side of the closure 48, as well as the lower ends of the angles I06 and I01,

' is secured to the respective side plates I5 and I6 by machine bolts I2I, Fig. 3. The elevator track I05 is thereby fixed between the pedestal and head casting and the closure 48 provides a chain guard therebetween.

The elevator of the present invention employs but a single endless chain and the spacers between the respective links thereof are rollers I which ride upon the channel III as they travel along the same. Every third link of the chain I00 is provided with a flight I comprising outwardly extending brackets I20 and I21, each flared laterally with respect to the center of the chain. A pin I28 extends between the upper ends of each pair of brackets I26 and I2'I and supports a roller I30 adapted to engage a container for pushing the latter upwardly and over the drive sprocket 93.

The containers are fed onto the upper reach of the elevator chain I00 by the gravity chute I, hereinbefore mentioned, as seen in Fig. l. The gravity chute I has a lower wall I terminating adjacent the elevator chain and also has side walls I35 secured to the sides of the closure to support the discharge end of the gravity chute adjacent the elevator chain.

The containers gravitate along chute I in a steady stream toward the elevator and fall one after another into successive pockets I40 formed between the pusher rollers I30 of the chain I00. The containers fall into the respective pockets I40 and are supported on the inwardly extending flanges I09 and H0 of the elevator track I05. The upper reach of the chain is disposed at such an angle as to assure that each container will be supported in its respective pocket I40 as the containers are elevated.

The pusher roller I30 are so disposed relative to the longitudinal axes of the respective containers engaged thereby that the periphery of each roller engages the periphery of a container, i. e., the rollers have single line contact with the respective containers. Therefore, while the containers are pushed up the inclined track I05 they are free to roll upon the inwardly extending flanges I09 and H0 thereof and also are free to rotate with respect to the pusher rollers I30. Accordingly, scraping of the containers along the track I05 and against the pusher rollers I30 is minimized and the containers are elevated with the least possible resistance to the drive mechanism for the chain I00.

The circular sections 5| of the head casting 41 are each provided with inwardly extending flanges I4I which are tangent with respect to the flange I09 and H0 of the track I05 to form a continuation thereof. The circular sections 5| are also provided, adjacent their peripheries, with inwardly extending flanges I43 and the spaces between the flanges I 4| and I43 provide a track I45 around the sprocket 03. Therefore, as the containers leave the upper end of the track I05 they pass into the track I45 and are maintained within their respective pockets I40 as the chain I00 travels around the sprocket 93.

As the chain I00 begins its descending reach, the pockets I40 are inverted so that the containers will normally gravitate toward the feed valve 3. The valve housing 21 is provided with inclined surfaces I48 above the upper margin 39 of the inlet 3|. These surfaces I48 are tangent 5 to the ends of the flange I43 at the periphery of the circular sections 5| and are parallel to the normal pitch line of the descending reach of the chain I00. Consequently, the containers are maintained within the pockets I40 until they pass the upper margin 39 of the inlet 3I and thereafter are free to gravitate toward the turret pockets 31 as the chain moves past the inlet 3|.

The present apparatus is adapted to be operated at a high speed in which case the containers conveyed over the drive sprocket 93 are substantially pushed in a steady stream by the respective pusher rollers I30. While the containers are thus pushed, they are guided by the arcuate track I45 and subsequently descend toward the inlet opening 3| of the valve housing. In order to assure that containers fed at such speed will transfer from the chain pockets I40 to the turret pockets 31 a stripper guide I50 is provided.

The stripper guide comprises a pair of stripper rails I5I spaced apart and in alignment with the respective inside flanges I4I on the inner faces of the side plates 5!. The rails I5I are formed as an integral part of a casting I55 and" each of them is reinforced by a triangular shaped web I56 extending rearwardly from the rails. The webs I56 are joined by a web I59 extending normal to the chain I and rearwardly therefrom to the apex of the triangular webs where the latter are joined by a transverse portion I60.

The casting I55 is mounted between the side plate I and is suitably secured in place opposite the inlet 3I by bolts (not shown). The upper end of each rail I5I abuts against the lower end of the inside flanges I4I and the descending reach of the chain I00 passes between the rails I5I. The rails I5I are curved to guide the containers out of the chain pockets I40 and into a substantially vertical path which is tangent to the path the containers will travel while in the turret 36. The lower ends of the stripper rails I5I terminate adjacent the lower margin 38 of the inlet 3|.

It may sometimes happen that containers rebound from the outside flanges I43 toward the chain pockets as the containers approach the inlet opening 3I. Consequently, without the stripper guide I50 such containers would be carried beyond the desired path and might become jammed between the lower margin of the inlet opening 3I and the pusher roller I and would, therefore, be crushed or damaged due to shock so that they would not withstand the cooking pressure to which they are subsequently subjected. However, containers that rebound as aforesaid are positively deflected from the chain pockets into the turret pockets by the stripper I50 and damage to the containers is, therefore, avoided.

The lower reach of the chain I00 will normally hang in a slight catenary curve or in other words, will droop and when operating will vibrate relative to the normal pitch line between sprockets 93 and 86. Asseen in, Fig. 1, the stripper guide casting I55 is provided with a stabilizer shoe I65 which extends parallel to the lower reach of the chain I00 and opposite the inlet 3| of the valve. Thi shoe I65 is so positioned that the spacer rollers I24 of the chain I00 will normally engage the same when the chain is on its pitch line.

Consequently, as the links of the elevator chain I 00 leave the drive sprocket 93 their spacer rollfers I24 engage the shoe I65. and the normal vibratory action of the chain is, accordingly, minimized.

The maintenance of the chain on the normal pitch line thereof as the containers flow into the turret pocket is very important. It is apparent that movement of the chain outwardly from the inlet opening is limited by the shoe I65. The chain, however, tends to droop toward the opening 3I and, therefore, the chain must be maintained at a proper tenseness between the two sprockets 93 and 86. This is essential, otherwise the pusher rollers I30 are likely to extend into the opening 3I and are liable to become caught on the turret or on the lower margin 38 of the inlet 3|.

In order to maintain the elevator chain under tension the floating sprocket 86 is associated with a tension carriage I10 (Figs. 3 and 4). As hereinbefore explained, the sprocket 86 is secured to a shaft 85 having its ends rotatably mounted in bearings 18 and 10 formed as a part of the yoke 80. These bearings have parallel faces HI and fit into the respective guide slots 11 for sliding movement longitudinally with respect to the elevator housing 45. The yoke has legs I12 and I13 extending downwardly along the longitudinal axis of the housing 45 and has a threaded boss I14 at its bight. A rod I15 has one end threaded into the threaded boss I14 of the yoke and is secured thereto by a tapered pin I16 (Fig. 4). The rod I15 also extends downwardly along the longitudinal axis of the elevator housing and fits through an aperture I80 in the bottom of the casting 10 adjacent the standard 12.

A cylindrical cup I8I is formed concentric to the aperture I80 on the underside of the casting 10 and a compression spring I82 is arranged in this cup I 8I and around the shank of the rod I15. The spring I82 normally extends beyond the rim I83 of the cup I81 and is compressed byan adjusting nut I84 which is threaded onto the rod I15. The spring I82 in the present instance is of a construction calculated to exert approximately 340 pounds pressure when compressed by the adjusting nut I84 to a length disposing the outer end of the spring approximately A; of an inch from the rim I83 of the cup I8I. The nut I84 is secured in its position of adjustment by a locking sleeve I85 threaded onto the end of the rod I15 to tightly engage and lock the nut I84 on the threads of the rod.

By the foregoing arrangement, the elevator chain I00 is properly tightened and any manufacturing tolerances, i. e., variations in link length or the like, are taken up by the spring I82. Consequently, as the chain travels around the sprockets 93 and 86, a pulsation of the floating sprocket is permitted. In other words, the bearings 18 and 19 slide in the slots 11 and the yoke 80 is constantly urged downwardly by the compression spring I82 to keep the sprocket 86 tightly against the endless chain I00.

As the chain I00 and sprockets 93 and 86 wear due to constant running, the floating sprocket 86 is free to move by the influence of the compression spring I82. The compression spring will urge the yoke, its floating bearings, and the sprocket 86 longitudinally away from the drive sprocket 03 and maintain the chain I00 under tension. However, when wear of the chain, and sprockets is thus compensated for, the adjusting nut I84 becomes spaced further from the rim 183 of the cup I 8| than it was in its original setting and the compression of the spring I82 will, accordingly, be reduced. Therefore, it becomes necessary to readjust the nut I84 back into the predetermined spaced relation with re- 7 spect to the rim I33 in order to obtain the desired tension of the elevator chain, as hereinbe fore explained.

In addition to maintaining a proper tension on the elevator chain I the relationship of .the adjusting nut I84 to the rim I83 of the cup IBI provides a safety feature. Should the spring I82 break or otherwise fail to bear against the nut I84 and thereby release the tension of the chain I80, the adjusting nut [83 will abut-against the rim I83 of the cup. The floating bearings 18 and i9 and sprocket 86 are thereby prevented from sliding to the upper end of the slots TI. Therefore, the floating bearings can only move upwardly a limited distance dependent upon the distance of the adjusting nut from the rim 183 of the cup and, accordingly, excessive drooping of the chain is prevented. By thus preventing excessive drooping of the chain, the pusher rollers I39 are prevented from entering the inlet opening 3| of the feed valve. Therefore, the rollers I38 will not extend into the path of the turret pockets 3? and jamming of the rotary turret 36 as the latter rotates within the housing 2! is thereby prevented. Moreover, the rollers I 30 are also thereby prevented from hooking onto the lower margin 38 of the inlet 3| and excessive damage to the apparatus avoided.

While I have described a particular embodiment of the present invention, it will be understood that various changes and modifications may be made without departing from the spirit of the invention. I, therefore, do not limit myself to the specific arrangement disclosed, but desire to avail myself of such modifications and alterations as come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In an endless chain conveyor arranged to travel over a driven and a floating sprocket, a stationary support, means mounting said floating sprocket on said support for movement toward and from said chain, said mounting means having a threaded shank extending for axial sliding movement through said support in the direction of movement of said mounting means toward said chain, a spring encompassing the free end of .said shank and engaging said support, an adjusting nut on said shank beyond said spring for compressing said spring whereb the latter exerts a predetermined spring load to said floating sprocket to maintain the latter in tensioning en- :gagement with said chain, and means spaced from said adjusting nut and engageable by the same in the event of spring breakage for limiting movement of said floating sprocket away from said chain to thereby prevent excessive drooping of said chain. 2. A tension device for an endless web conveyor arranged to travel over spaced driven and floating wheels, comprising a stationary support having uideways formed therein, means for mount- :ing said floating wheel for sliding movement with respect to said guideways, yieldable means for urging said mounting means in a direction away :from said driven wheel, and adjustable means associated with said mounting means and said yieldable means for establishing a predetermined load against said floating wheel, said adjustable means being disposed to engage a portion of said stationary support in the event of failure of said yieldable means whereby to prevent excessive drooping of said endless web between said wheels.

3. A tension device for an endless web conveyor including spaced driven and floating wheels comprising a stationary support having guideways formed therein, means for mounting said floating wheel for sliding movement relative to said guideways, yieldable means operatively associated with said mounting means and bearing against said stationary support for urging said mounting means in a direction away from said driven wheel for maintaining said endless web at a predetermined tenseness, and means engaging said yieldable means and movable with said mounting means adapted to engage said stationary support incident to excessive relaxation of said yieldable means for limiting movement of said mounting means toward said driven wheel to thereby prevent drooping of said endless web.

a. A tension device for an endless chain trained around a driven and a floating sprocket comprising a stationary support having guideways in its side walls extending parallel to an axis extending from one to the other of said sprockets, means for mounting said floating sprocket for sliding movement relative to said guideways, yieldable means for urgingsaid mounting means in a direction away from said driven sprocket for tensioning said endless chain, adjustable means operatively associated with said yieldable means for exertin a predetermined load to said floating sprocket for maintaining said endless chain under a predetermined tension, and means on said stationary support adapted to be engaged by said adjustable means upon undue yielding of said yieldable means for limiting movement of said mounting means toward said driven sprocket to thereby prevent excessive drooping of said endless chain.

5. A tension device for an endless chain arranged to travel over a driven and a floating sprocket, a stationary support having parallel guideways extending in the general direction from said driven to said floating sprocket, means supported in said guideways for mounting said floating sprocket for sliding movement relative thereto, said means having a portion thereof extending from said stationary support, yieldable means associated with said extended portion of said 'mountin means for engagement with said stationary support, adjustable means on said extended portion for urging said yieldable means toward said stationary support and for urging said mounting means away from said driven sprocket, and means on said stationary support for engaging said adjustable means upon excessive yielding of said yieldable means to thereby limit movement of said mounting means toward said driven sprocket.

6. A tension device for an endless chain trained around a driven and a floating sprocket comprising a stationary support, a yoke having parallel legs provided with bearings rotatably supporting said floating sprocket, means on said stationary support for receiving said'bearings for supporting said floating sprocket for sliding movement toward andfrom said drivensprocket, a rod extending from said yoke, rearwardly of the legs thereof and through an opening provided in said stationary support, a compression spring encircling the extended end of said rod exteriorly of said support, means on said rod for'compressing said spring and for drawing said yoke and floating sprocket in a direction away from said driven sprocket for exerting a predetermined spring load upon said endless chain,'and means on said stationary support adapted to be spaced from said spring compressing means and for engagingthe latter in the event of excessive relaxation of said compression spring to thereby prevent excessive drooping of said chain.

7. A tension device for an endless chain trained around a driven and a floating sprocket comprising a stationary support having guide slots formed in opposite Walls thereof substantially parallel to an axis extending from said driven sprocket through said floating sprocket and having an aperture aligned with said axis rearwardly of said floating sprocket, a yoke having parallel legs provided with bearings extending into said guide slots for supporting said floating sprocket for rotation and sliding movement relative to said support, a rod extending rearwardly from the bight of said yoke and through the aperture in said stationary support, a compression spring circumscribing the extended end of said rod, adjustable means on said rod for compressing said spring to exert a predetermined spring load upon said chain, and means on said stationary support for engaging said adjustable means in the event of failure of said compression spring for limiting movement of said floating sprocket away from said chain to thereby prevent drooping 'of said chain.

8. A tension device for an endless chain trained around a driven and a floating sprocket comprising a stationary support having guide slots formed in opposite walls thereof substantially parallel to an axis extending from said driven sprocket through said floating sprocket and having an aperture aligned with said axis rearwardly of said floating sprocket, a yoke having parallel legs provided with bearings extending into said guide slots for supporting said floating sprocket for rotation and sliding movement relative to said support, a rod extending rearwardly from the bight of said yoke and through the aperture in said stationary support, a compression spring circumscribing the extended end of said rod, adjustable means on said rod for compressing said spring to exert a predetermined spring load upon said chain, and means on said stationary support for maintaining said compression spring in alignment with said rod and for engaging said adjustable means in the event of failure of said compression spring for limiting movement of said floating sprocket away from said chain to thereby prevent drooping of said chain.

9. A tension device for an endless chain trained around a driven and a floating sprocket comprising a stationary support having guide slots formed in opposite walls thereof substantially parallel to an axis extending from said driven sprocket to said floating sprocket and having an aperture aligned with said axis, a yoke arranged within said stationary support having parallel legs provided with bearings extending into said guide slots for sliding movement, means for mounting said floating sprocket for rotation between said bearings, a threaded rod extending rearwardly from the bight of said yoke through the aperture in said stationary support, said stationary support having a cup shaped flange circumscribing the extended end of said threaded rod, a compression spring surrounding the threaded rod and seated within the cup shaped flange of said stationary support, and an adjusting nut threaded onto said threaded rod and against the free end of said compression spring for compressing the latter until its free end is disposed a predetermined distance outwardly from the rim of said cup shaped flange whereby in the event of excessive relaxation of said compression spring said adjusting nut will engage the rim of said cup shaped flange for limiting movement of said floating sprocket away from said chain to thereby prevent excessive drooping of said chain.

THOMAS B. KEESLING.

REFEREIJCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 18,006 Hall Mar. 24, 1931 880,303 Hetherington Feb. 25, 1908 2,229,973 Hormel Jan. 28, 1941 2,355,100 Nordquist Aug. 8, 1944 2,463,437 Steiner Mar. 1, 1949 FOREIGN PATENTS Number Country Date 448,828 Germany Aug. 30, 1927 

